What this breaker is and what the ratings mean for fit
The Siemens 3VA1340-4GE42-0AA0-ZD00 is a 4-pole IEC frame 400 circuit breaker in breaking capacity class S, with a rated ultimate short-circuit breaking capacity (Icu) of 36 kA at 415 V AC. That 36 kA at 415 V means it can safely interrupt fault currents up to that level without welding contacts or cascading failure upstream — critical for panel selectivity studies where the upstream device must see the fault and clear it before the breaker reaches its limit. The thermal-magnetic trip unit is a TM220 (ATFM) with In = 400 A. Overload protection (Ir) adjusts from 280 A to 400 A; short-circuit protection (Ii) is fixed at 10 × In. The 100% N-conductor protection means the neutral pole is fully rated — no derating needed for unbalanced loads or harmonic-rich circuits common in DC Power OEM builds. This variant includes a nut keeper kit and is specified for DC Power OEM in China. The nut keeper kit simplifies panel mounting by retaining the mounting nuts during installation — a small time-saver on repetitive builds.